[EM] Explaining PR-STV

[Raph Frank]

On Sun, Aug 30, 2009 at 6:55 PM, Kathy Dopp<kathy.dopp at gmail.com> wrote:
> Yes.We agree. Then you agree that the IRV/STV method should not be
> used since it virtually always fails the majority criteria quotas that
> it sets and fails to elect a sufficient number of candidates to fill
> all the seats?

And replaced with what?

I wouldn't vote for IRV as a single seat method (except perhaps
relative to plurality).

I agree it isn't a good method for single seat districts.

> Often IRV/STV is sold as replacing top-two runoff systems, thus why do
> you support replacing a majority system with a non-majority IRV/STV
> system, necessitating that any jurisdiction that adopts RCV or IRV
> eliminates any of its majority requirements?

Well different voters vote in the run-off.  If a voter doesn't fully
rank, then you could argue that they had abstained from the subsequent
rounds.

>> Right, IRV is not a good single seat method.
>
> The Aspen election used STV and that is how the nonmonotonicity
> resulted, in a multi-seat city council election.

Hmm, I assumed by IRV, they meant the single seat method.

>
> You should do due diligence to investigate the facts, actually read
> the articles or reports on STV in Aspen and Burlington

I read the linked page.  I assumed that IRV meant the single seat method.

Is this not the case?  The council is elected from a single multi-seat district?

> etc. so you
> don't confuse your imagination of what STV/IRV do with the reality of
> what they do,and be willing to tell people the truth about how IRV/STV
> really works, namely that it removes their voting right to cast a vote
> for a candidate that positively effects that candidate's chances to
> win in both IRV and in STV.

I still stand by my claim that it is advantageous on average for multi-seat.

In my experience, the non-monotonicity only can be determined after the fact.

>> However, the impact of the problems are lessened with PR-STV.
>
> Again, the majority-favored, most popular city council candidate who
> lost thanks to STV's nonmonotonicity and all his supporters in Aspen
> might disagree with you.

So, Aspen is single seat IRV then?

>> In real elections, ranking a candidate higher is likely to help the candidate.
>
> Or in STV/IRV it may hurt that candidate's chances of winning or not
> affect it at all.

Are you saying that the candidates don't understand the system either
(or at least don't understand the best way to get elected)?

Polls aren't accurate enough to take advantage of the
non-monotonicity.  On average, you help a candidate by ranking the
candidate higher.

> Yes, but it certainly advantages the less popular candidates and it
> certainly is possible for voters of more widely supported candidates
> to be penalized by it and for nonmonotonicity to cause a
> majority-opposed candidate win while a majority-favorite loses in
> STV/IRV.

Again, the tread is about the multi-seat PR version.

> It is impossible to take advantage of lots of very negative things in
> life, does that mean we should support every negative thing that some
> advantage can not be planned of it in advance?

No, the point is that on average you are better off ranking a
preferred candidate higher.

> I truly don't have time to continue rebutting what I consider to be
> wholly irrational and worst imaginable method of counting votes,
> STV/IRV.

I think you are letting your dislike for IRV spill over into PR-STV.